Most of the free-flowing, more especially powder-form, fabric detergents commercially available today are produced by spray drying or at least using spray-dried components. A particularly well-known technique is the so-called spray-mixing process. In this process, a substantial percentage of the final detergent mixture is converted by spray-drying into a free-flowing or powder-form material to which the remaining components of the final detergent are then added. In this regard, it is known in particular that the builder component, if desired together with mutual salts, may be obtained as a powder-form solid product by spray drying, and the surfactant components are subsequently added to the powder-form material thus prepared.
So far as the surfactant components are concerned, paramount importance is attributed, among the anionic surfactant components, to alkyl benzenesulfonate (ABS) which is generally used in the form of its sodium salt, usually in conjunction with nonionic surfactants, such as for example alcohol ethoxylates.
Where surfactant mixtures of the type herein are incorporated by mixing into preformed powder-form detergent components, it is important to ensure that the free-flowing powder form is sufficiently maintained in the end product. In the normal use of the surfactants and surfactant mixtures on an industrial scale, particularly those of the above-mentioned type based on ABS in admixture with nonionic surfactants, there is a practical limit of about 12% by weight surfactant in the detergent as a whole. With higher surfactant contents, the end product easily becomes tacky, particularly in a spray-mixing process. This in turn gives rise to an undesirable change in the flow properties of the end product.
An object of the present invention is to provide new surfactant mixtures which are easy to process on an industrial scale, even when used in higher concentrations than before, which do not adversely affect the flow properties of the final detergent powder and which, in addition, are at least comparable with known surfactant mixtures in the effect they have on the washing result. More particularly, an object of the present invention is to provide surfactant mixtures of the type described which are pourable and pumpable at room temperature and, as a result, can be incorporated particularly easily in preformed powder-form components of a detergent composition. Despite the free-flowing character of the surfactant mixtures, however, the final dertergent powders should not develop any undesirable tackiness at high surfactant contents so that their fluidity or free-flow properties are not impaired.